This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Iron-sulfur ([Fe-S]) clusters are simple inorganic groups found in various organisms. The proteins holding the [Fe-S] clusters can have various unique functions: electron transfer, gene regulation, environmental sensing, and substrate activation. In particular, among several [Fe-S] cluster assembly and transfer protein systems, IscU is a very fascinating protein because of its unique biological functions and flexible characteristics. To date, it is believed that IscU assembles the [2Fe-2S] cluster and transfers it to ferredoxins. However, the actual mechanisms involved in the cluster assembly and transfer have not been described previously in the molecular level. Therefore, by investigating IscU with the nuclear magnetic resonance (NMR) spectroscopy, we are expecting that the structural dynamics of IscU can be determined, which may explain the molecular mechanisms of IscU as well. In addition, we are trying to analyze the paramagnetic signals of holo-IscU and to investigate the characteristic pattern of coordinating the [Fe-S] cluster. This may elucidate many unknown properties of the interaction between IscU and the [Fe-S] cluster.